﻿224 Reviews — Nicholson s Life-History of the Earth. ■ 



Under the " Biological Eelations of Fossils " we are told that 

 fossils " have relations of the. most complicated and weighty character 

 with the numerous problems connected with the study of living 

 beings, or, in other words, with the Science of Biology." To such an 

 extent is this the case that no adequate comprehension of Zoology 

 and Botany, in their modern form, is so much as possible without 

 some acquaintance with the types of animals and plants which have 

 passed away." 



Passing to the section of the work devoted to Historical Palaeon- 

 tology, there are a few points to which the attention of our readers 

 is particularly directed. At the end of each chapter, representing a 

 geological period, Prof. Nicholson has introduced a list of the more 

 important and accessible works and memoirs bearing on the period, 

 or its fossils, treated of, vmder the general heading "Literature." 

 This feature has already been carried out by some G-erman writers, 

 notably by Carus and Gerstaecker in their "Handbuch der Zoologie," 

 and its adoption by Prof. Nicholson will, we think, be of much 

 assistance to the student, and add greatly to the value of the work. 

 The stratigraphical sub-divisions of each period, irrespective of 

 description, are well shown in the form of woodcuts representing 

 vertical " generalized sections," demonstrating the order of suc- 

 cession of the various groups of strata, in one or other, and 

 sometimes several of the countries in which the rocks comprising 

 the period are best developed. Supplementary to these "general- 

 ized sections" are occasionally given "tabular views," in which 

 are shown the equivalent sub-divisions of a formation in various 

 countries, ranged in parallel columns. We can only notice with 

 brevity a few of the more strictly important palceontological facts 

 brought forward by the author. The reasons for supposing the 

 existence of an abundance of life during the Laurentian period are 

 clearly brought forward. Whilst speaking of Eozoon, the author 

 considers " that the balance of evidence up to this moment inclines 

 decisively to this view" {i.e. as to its organic nature). As a line of 

 demarcation between the Cambrian and Silurian formations. Dr. 

 Nicholson takes the Tremadoo slates, as proposed by Dr. Hicks. 

 The structure of the Graptolites is entered into at some length, 

 as might be expected from the author's well-known acquaintance 

 with this family ; he regards them as an ancient and peculiar group 

 of Hydroida, and does not accept the Polyzoal affinities advocated by 

 some writers. With regard to the advent of Vertebrates, we are 

 reminded that the curious bodies from the Lower Silurian rocks of 

 Russia, termed Conodonts by Pander, may yet prove to be the teeth 

 of fishes, recent researches of Prof. Newberry having a tendency to 

 establish Pander's original conclusion as correct. We regard Prof. 

 Nicholson's remarks on the Devonian question with keen interest. 

 With the view that the " Devonian formation has in nature no 

 actual existence," advocated by some authorities, he does not concur, 

 but considers that its flora and fauna, as a whole, are quite distinct 

 both from the Silurian and Carboniferous. "This conclusion may be 

 regarded as sufficiently proved even by the phenomena of the 



